Precipitator charge indicator



J. E. COOLIDGE, JR ET AL 2,861,261

PRECIPITATOR CHARGE INDICATOR Nov. s, 1958 Filed March 8, 1956 f721/67Zf0715 Zia/Emit Coolie? 2 ga /r. Georzgeffnvalz'nfia United States Patent 0 PRECIPITATOR CHARGE INDICATOR John E. Coolidge, Jr., Des Plaines, and George Konvalinka, Northbrook, Ill., assignors to Borg-Warner Corporation, a corporation of Illinois Application March 8, 1956, Serial No. 570,327

2 Claims. (Cl. 340-252) This invention relates to electric precipitatorsfor precipitating dust or smoke from the atmosphere. More particularly, the invent-ion relates to precipitators of the type in which air to be cleaned is first ionized by an ionizing device and thereafter passed through a precipitating device comprising a plurality of parallel plates, alternate plates being charged in one polarity and intervening plates being charged in the opposite polarity. The invention is primarily concerned with an indicator for indicating the presence of a charge on the plates of the precipitating device. In precipitators of the type to which the invention relates, a power pack supplies a high voltage to the parallel plates of the precipitator. It is important to the user of the device to be sure that voltage is being supplied to the collecting plates at all times when the precipitator is in use. In the past, precipitators have used indicating lights or meters which indicated voltage on the low voltage side of the power pack. However it is possible that because of a broken connection or a bad vacuum tube, voltage would be indicated at the power pack but no voltage would be transmitted to the collecting plates and therefore there would be no charge upon them and the plates would not function as collectors of dust.

It is among the objects of thepresent invention to provide a small inexpensive indicator which can be readily attached to existing precipitators and will indicate the presence of or absence of a charge on the collector plates.

It is a further object of the present invention to provide a small inexpensive indicating device which will not use any appreciable amount of current.

A further object of the invention is to provide an indicator light using a standard neon glow lamp which is readily available from commercial sources and is very inexpensive. The above and other objects and features of the invention will be made fully apparent to those skilled in the art from a consideration of the following detailed description taken in consideration with the accompanying drawing in which:

Fig. l is an elevational view partly in cross-section of an electric precipitator showing our indicating device attached thereto.

Fig. 2 is an elevational view partly in cross-section taken on the line 22 of Fig. 1.

Fig. 3 is a perspective view of the holding clamp for the indicator light.

Referring to the drawing the reference numeral indicates an electrical precipitator of a small size which is readily portable and is commonly designated as a room size precipitator. It comprises a cabinet 11 Which encloses the device on the sides, a front grille 12 on one end and a rear grille 13 on the other. Adjacent the rear grille 13 is a fan 14 which operates in conjunction with a venturi 15 to move air through the precipitator. Adjacent the venturi 15 is an ionizing section 16 which comprises a frame 17 supporting a plurality of ionizing wires 18. Air passes from the ionizing section 16 through a collector section 19 which comprises a plurality of spaced parallel metal plates 20 and 21. The plates 20 are adapted to be charged with a negative polarity and the plates 21 are adapted to be charged with a positive polarity by a power pack 22. The power pack 22 may be of any standard design which will deliver a voltage of the order of 8,000 volts. I

In operation air is pulled by the fan through the rear grille 13 and is propelled by the fan through the ionizing section 16 where the charge on the ionizing wires 18 places a charge on the dust particles in the air. Theair then passes through the collector section where the particles are attracted to plates carrying a charge of the opposite polarity and the cleansed air then passes through the front grille 12 into the room. f

The present invention provides an indication of a charge on the collector plates 20 and 21 by a small neon glow tube23 which is supported on one of the plates. 20 or 21. As is shown more clearly in Fig. 2 the support 24 for the glow tube may comprise a single piece of spring-like conducting material preferably copper with one portion 25 formed to provide a clip for attaching the device to the plate 20 or 21 and a second portion 26 bent to provide two wings 26 and 26a which enclose the tube 23.

The glow tube 23 is provided with two lead-in wires 27 and 28. The lead-in wire 27 is pressed against the support 24 by the spring-like action of the wings 26 and 26a pressing the tube 23 into place. The lead-in wire 28 extends parallel to the collection plates 21 and 20 and is spaced mid-way between them. Lead-in wire 28 should be at least 1 inch in length in the precipitator described to give a stable discharge.

In operation the indicating glow tube 23 in its support 24 is positioned on the front of one of the collector plates in a position behind the front grille 12 where it can be seen from the outside of the cabinet. The lead-in wire 27 should contact a portion of the support 24 so that electrical contact is maintained between it and the plate 20. The lead-in wire 28 should extend parallel to the collector plates 20 and 21 and should be positioned approximately mid-way between them so that an air space is maintained on each side of said wire. The lead-in wire 28 acts like a probe and when a charge is placed on plates 20 and 21 a corona discharge is produced at the probe 28 causing the neon glow tube 23 to light. In effect this corona discharge serves as a large dropping resistor to the neon bulb discharge so that sufficient current passes through the bulb to cause it to be activated and produce light. Although the device may be attached to either the positive or the negative plate it has been found that a direct connection to the negative plate produces a more stable corona discharge at the probe causing a more steady emission of light than the contrary arrangement wherein the bulb is supported on the positive plate.

When the electric precipitator is energized, if there is a charge on the plates 20 and 21, the glow tube 23 will glow immediately and the user is assured that a charge is present. If for any reason the voltage to these plates should be discontinued or drop to a low value, the glow tube 23 will not emit light and the user is immediately warned that the device is not operating properly even though the fan 15 may be turning and the power pack may be drawing current.

The invention has been described with a neon glow tube and we prefer to use this type of tube because of its dependability and low cost. However, other types of gaseous discharge tubes may be used in place of the tube described.

While there has been herein described a preferred embodiment of the invention, other embodiments within the scope of the appended claims will be apparent to those skilled in the art from the consideration of the form shown and the text hereof.

What is claimed is:

1. Adevice for indicating a charge on the collector plates of an electricalprecipitator having a plurality of spaced collector plates adapted to be charged with high voltage comprising a neon glow tube having two lead-in wiresia clip for. attaching said tube on one of the collector plates so that its emitted light may be visible from outside of the precipitator, with one of said lead-in wires being electrically connected to said one collector plate and the other lead-in wire extending approximately mid-way between said onecollector plate and an adjacent collector plate and parallel with said plates to act as a probe whereby visible light will be emitted by said tube when a subs'tantialdifference in voltage exists between said adjacent collector plates.

2. In an electrical precipitator having a plurality of spaced collecto r plates adapted to be charged, a device for indicating a charge on said plates comprising, a gas filled glow tube having lead-in wires, means to position said tube on one of said collector plates including a unitary clip of spring-like conducting material formed with a base having two wing portions extending forwardly therefrom and normally urged together to enclose the tube and an elongated portion bent back from the base and normally urged toward the back of said base so that it may frictionally hold on said collector plate and with one of said lead-in wires being electrically connected to said one of said collector plates and another of said lead-in wires extending in the space between adjacent collector plates to act as a probe whereby the glow tube will emit light when a substantial difference in voltage exists between the adjacent collector plates.

References Cited in the file of this patent UNITED STATES PATENTS 1,884,950 Woodring Oct. 25, 1932 2,030,491 Abadie Feb. 11, 1936 2,475,356 Meschter July 5, 1949 2,591,898 Webster Apr. 8, 1952 FOREIGN PATENTS 763,018 Germany Mar. 1, 1954 677,375 France Dec. 9, 1929 

